This invention relates in general to a dishwashing machine and, in particular, to a control system for automatically actuating the operating components of a dishwashing machine such as dishwasher pumps, conveyor motor, exhaust fan motor, booster heaters and tank heaters.
More specifically, this invention relates to a dishwashing machine control system whereby energy consumption of a dishwashing machine is reduced by controlling the operation of various operating components of the machine.
Commercial dishwashing machines, such as are widely used in restaurants, generally involve a plurality of operator initiated steps such as, for example, closing drain valves; opening fill valves; filling tanks to the proper levels; actuating tank and booster heaters and so forth. Generally, prior art commercial dishwashing machines must be operated for sustained periods of time with considerable waste of electrical energy.
Due to the fact that it is both time-consuming and inefficient to continually turn the machine on and off as use is desired, the dishwashing machine is commonly turned on in the morning and remains in continuous operation until the last dishwashing operation is completed. Since the dishwashing machine is only used intermittently during the course of the day, there are times during the day when the machine is energized and not in use. During this time, the heating elements are actuated to maintain the temperature of the water at a desired level to provide sufficient hot water for the various cycles of the dishwashing machine. Also, various other components of the dishwashing machine such as the conveyor dishwasher motor, pumps and exhaust fan motor also remain electrically actuated. Because of the continuous operation of these heaters and various other components, the dishwashing machine needlessly consumes electrical energy increasing the cost of its operation and being counter-productive to the national objective of energy conservation.
In order to accomplish an effective and efficient washing operation, hot water is generally dispensed in prior art dishwashing machines onto the dishes during a pre-wash cycle which occurs as soiled dishes enter the machine. Such known dishwashing machines often have tank heaters which heat the water for the pre-wash cycle of the dishwashing machine. However, the tank heaters require actuation before any dishes enter the machine, because the water must be sufficiently hot to pre-wash the dishes as they enter the machine thereby requiring the tank heater to be on and ready all the time. Dishwashing machines in the prior art also have booster heaters which provide hot water for the final rinse spray when the soiled dishes reach the final rinse cycle. These booster heaters require costly energization as soon as the washing cycle was commenced to provide sufficiently heated water for the final rinse cycle.
In previous dishwashing machines, the on-off cycle of these heaters was independent of the washing and rinsing operations of the dishwashing machine, thereby both the booster heater and the tank heaters had to be continually energized to insure that the machine always had a sufficient supply of hot water as it was needed.
Such simultaneous operation of both heating elements, the booster heater and the tank heater, results in a costly increase in the kilowatt hour and energy demand required by the dishwashing machine.